The wording could be a bit better because I was a bit confused too.
Assuming that you know how to compute the domain and ranges of these elementary functions then this is how you should be reading the question:
Which two of the following functions have the same domain and range as each other?
Question is asking, which pair of functions have domain and range same as each other.
- x^3 domain = R (All Real numbers); Range = R
- |x| domain = R; Range = R+ including 0, (All positive Real Numbers and zero)
- Root(x) domain = R+ including 0; Range = R+ including 0
- Root(x^2) domain = R Range = R+ including 0
- 1/x domain = R Range = R except 0 (All Real numbers except 0)
You can see that Option B and D have domain and Range. Hence BD is the answer.